JP5638169B2 - SOUND GENERATOR, SOUND GENERATOR, AND ELECTRONIC DEVICE - Google Patents

Description

  Embodiments of the disclosure relate to a sound generator, a sound generation device, and an electronic apparatus.

  Conventionally, it is known that an acoustic generator typified by a piezoelectric speaker can be used as a small and thin speaker. Such a sound generator can be used as a speaker incorporated in an electronic device such as a mobile phone or a thin television.

  As an acoustic generator, for example, there is one including a vibrating body and an exciter (piezoelectric vibrating element) provided on the vibrating body (see, for example, Patent Document 1). This is a configuration in which a vibrating body is vibrated by a piezoelectric vibration element, and a sound is generated using a resonance phenomenon of the vibrating body.

Japanese Patent Laid-Open No. 2004-23436

  However, since the sound generator described above is configured to generate sound pressure by resonance of the vibrating body itself, for example, a sound having a frequency that becomes a resonance peak in the frequency characteristic of sound pressure is kept at a high sound pressure. If it continues to be generated, stress concentrates on the boundary of the joint due to vibration of the vibrating body, and the piezoelectric vibrating element may be peeled off from the vibrating body, thereby changing the frequency characteristics.

  One aspect of the embodiment is made in view of the above, and includes an acoustic generator, an acoustic generator, and an electronic device that can prevent a frequency characteristic from fluctuating due to an exciter being peeled from a vibrating body. The purpose is to provide.

An acoustic generator according to an aspect of an embodiment includes a vibrating body, an exciter that vibrates when an electric signal is input thereto, a joint that joins the exciter on the vibrating body, and the vibrator to the vibrating body. And at least a part of the outer periphery of the joint is located inside the outer periphery of the exciter, and a part of the cover is between the vibrating body and the exciter. A part of the covering portion has an asymmetric shape with respect to the central axis of the exciter perpendicular to the vibration surface of the vibrating body .
An acoustic generator according to another aspect includes a vibrating body, an exciter that vibrates when an electric signal is input, a joint that joins the exciter on the vibrating body, and the vibration from the exciter. A covering portion provided over the body, wherein at least a part of the outer periphery of the joint portion is located inside the outer periphery of the exciter, and a part of the covering portion is provided between the vibrating body and the exciter. Is interposed, and the joining portion and a part of the covering portion are in contact with each other, and the outer peripheral surface of the joining portion contacting the part of the covering portion has irregularities.
An acoustic generator according to another aspect includes a vibrating body, an exciter that vibrates when an electric signal is input, a joint that joins the exciter on the vibrating body, and the vibration from the exciter. A part of the outer periphery of the joint is located inside the outer periphery of the exciter, and the other part is located outside the outer periphery of the exciter. A portion of the covering portion is interposed between the vibrating body and the exciter.
An acoustic generator according to another aspect includes a vibrating body, an exciter that vibrates when an electric signal is input, a joint that joins the exciter on the vibrating body, and the vibration from the exciter. A covering portion provided over the body, wherein at least a part of the outer periphery of the joint portion is located inside the outer periphery of the exciter, and a part of the covering portion is provided between the vibrating body and the exciter. And a void is formed in a part of the covering portion.
An acoustic generator according to another aspect includes a vibrating body, an exciter that vibrates when an electric signal is input, a joint that joins the exciter on the vibrating body, and the vibration from the exciter. A covering portion provided over the body, wherein at least a part of the outer periphery of the joint portion is located inside the outer periphery of the exciter, and a part of the covering portion is provided between the vibrating body and the exciter. There is a gap between the covering portion and at least one of the vibrating body, the exciter, and the joint portion.

  According to the acoustic generator of one aspect of the embodiment, the bonding strength between the vibrator and the exciter can be improved, and the peeling of the exciter from the vibrator can be suppressed, and the frequency characteristics can be prevented from fluctuating. be able to.

FIG. 1A is a schematic plan view of the sound generator according to the embodiment. 1B is a cross-sectional view taken along line A-A ′ of FIG. 1A. FIG. 2 is a schematic plan view illustrating an example of the shape of the joint portion and the covering portion intervening portion illustrated in FIG. 1. FIG. 3 is an enlarged sectional view taken along line B-B ′ of FIG. 2. FIG. 4 is an enlarged cross-sectional view taken along line B-B ′ of FIG. 2, showing a modification of the sound generator according to the embodiment. FIG. 5 is an enlarged cross-sectional view taken along line B-B ′ of FIG. 2, showing a modification of the sound generator according to the embodiment. FIG. 6 is an enlarged cross-sectional view taken along line B-B ′ of FIG. 2, showing a modification of the sound generator according to the embodiment. FIG. 7 is an enlarged cross-sectional view taken along the line B-B ′ of FIG. 2, showing a modification of the sound generator according to the embodiment. FIG. 8 is a block diagram of the sound generator. FIG. 9 is a block diagram of an electronic device.

  Hereinafter, embodiments of a sound generator, a sound generator, and an electronic device disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

  1A is a schematic plan view of the acoustic generator 1 according to the embodiment as viewed from a direction perpendicular to the main surface of the vibrating body 10, and FIG. 1B is a cross-sectional view taken along the line A-A ′ of FIG. 1A. In FIG. 1B, for easy understanding, the sound generator 1 is expanded and deformed in the vertical direction.

  As shown in FIGS. 1A and 1B, the sound generator 1 according to the embodiment includes a vibrating body 10, an exciter (piezoelectric vibration element 20), and a frame body 30. Such an acoustic generator 1 is called a so-called piezoelectric speaker, and generates a sound pressure using a resonance phenomenon of the vibrating body 10 itself.

  The vibrating body 10 can be formed using various materials such as resin, metal, and paper. For example, the thin plate-like vibrating body 10 can be formed of a resin film such as polyethylene, polyimide, or polypropylene having a thickness of 10 to 200 μm. Since the resin film is a material having a lower elastic modulus and mechanical Q value than a metal plate or the like, the vibrating body 10 is made of a resin film to bend and vibrate the vibrating body 10 with a large amplitude so that the sound pressure is reduced. It is possible to reduce the difference between the resonance peak and the dip by widening the width of the resonance peak and reducing the height in the frequency characteristics.

  The piezoelectric vibration element 20 that is an exciter that vibrates when an electric signal is input is a bimorph type laminated piezoelectric vibration element. For example, the piezoelectric vibration element 20 includes a laminated body 21, surface electrode layers 22 and 23 formed on the upper and lower surfaces of the laminated body 21, and an external surface formed on the side surface where the end face of the internal electrode layer 24 of the laminated body 21 is exposed. Electrodes 25 and 26 are provided. Then, lead terminals 27 a and 27 b are connected to the external electrodes 25 and 26.

  The laminate 21 is formed by alternately laminating four piezoelectric layers 28a, 28b, 28c, 28d made of ceramics and three internal electrode layers 24. The piezoelectric vibration element 20 has a rectangular main surface on the upper surface side and the lower surface side, and the piezoelectric layers 28a and 28b and the piezoelectric layers 28c and 28d are alternately changed in the direction of polarization in the thickness direction. Polarized.

  When a voltage is applied to the piezoelectric vibration element 20 via the lead terminals 27a and 27b, for example, the lower surface side of the piezoelectric vibration element 20, in other words, the piezoelectric layers 28c and 28d on the vibration body 10 side contract, while the upper surface The piezoelectric layers 28a and 28b on the side are deformed so as to extend. As described above, the piezoelectric layers 28a and 28b on the upper surface side of the piezoelectric vibration element 20 and the piezoelectric layers 28c and 28d on the lower surface side exhibit opposite expansion and contraction behavior, and as a result, the piezoelectric vibration element 20 is bent bimorph-shaped. By vibrating, a certain vibration can be given to the vibrating body 10 to generate a sound.

  As an exciter that can be applied to the acoustic generator of the present embodiment, in addition to the piezoelectric vibration element 20, any exciter may be used as long as it has a function of receiving an electric signal and exciting it. It may be an electrodynamic exciter, an electrostatic exciter, or an electromagnetic exciter known as an exciter. Here, the electrodynamic exciter is such that a current is passed through a coil arranged between the magnetic poles of a permanent magnet to vibrate the coil. Further, the electrostatic exciter is such that a bias and an electric signal are passed through two metal plates facing each other to vibrate the metal plate. An electromagnetic exciter is such that an electric signal is passed through a coil to vibrate a thin iron plate.

  Here, as the material constituting the piezoelectric layers 28a, 28b, 28c, 28d, conventionally, lead-free piezoelectric materials such as lead zirconate titanate (PZT), Bi layered compounds, tungsten bronze structure compounds, etc. The used piezoelectric ceramics can be used.

  The material of the internal electrode layer 24 preferably contains a metal component made of silver and palladium and a material component constituting the piezoelectric layers 28a, 28b, 28c, 28d. When the internal electrode layer 24 contains the ceramic component constituting the piezoelectric layers 28a, 28b, 28c, 28d, the difference in thermal expansion between the piezoelectric layers 28a, 28b, 28c, 28d and the internal electrode layers 24, 24, 24. Thus, it is possible to obtain the piezoelectric vibration element 20 in which the stress due to the above is reduced.

  Further, as the wiring connected to the lead terminals 27a and 27b, in order to reduce the height of the piezoelectric vibration element 20, it is preferable to use a flexible wiring in which a metal foil such as copper or aluminum is sandwiched between resin films.

  The piezoelectric vibration element 20 configured as described above is bonded to the vibration surface 10a of the vibrating body 10 via a bonding portion 40 formed of an adhesive. The thickness of the joint portion 40 between the piezoelectric vibration element 20 and the vibrating body 10 is relatively thin, for example, 0.02 μm or more and 20 μm or less. Thus, when the thickness of the joint portion 40 is 20 μm or less, the vibration of the stacked body 21 can be easily transmitted to the vibrating body 10.

  An adhesive can be used as the joint portion 40, and known materials such as an epoxy resin, a silicon resin, and a polyester resin can be used, but are not limited thereto. In addition, as a method for curing the resin used for the adhesive, any method such as thermosetting, photocuring, and anaerobic curing may be used.

  Here, in the acoustic generator 1 according to the present embodiment, for example, a part of the adhesive application region is inside the outer periphery 20a of the lower surface of the piezoelectric vibration element 20, or due to solidification contraction, the outer periphery 40a of the joint portion 40. At least a part of is located inside the outer periphery 20 a of the piezoelectric vibration element 20. In other words, a portion (gap) where the joint portion 40 is not formed is provided in a part between the vibrating body 10 and the piezoelectric vibration element 20.

  In the acoustic generator 1 according to the present embodiment, a part of the covering part 50 described later is interposed in the gap (hereinafter, a part of the covering part 50 interposed in the gap is covered with the covering part interposed part). 41). As a result, the covering portion intervening portion 41 and the vibrating body 10 are joined, and the covering portion interposing portion 41 and the piezoelectric vibration element 20 are joined, so that they exist between the vibrating body 10 and the piezoelectric vibrating element 20. Compared to a configuration that does not have the covering portion intervening portion 41 in the gap, the bonding strength between the vibrating body 10 and the piezoelectric vibrating element 20 is improved, and the peeling of the piezoelectric vibrating element 20 from the vibrating body 10 can be suppressed.

  In particular, by providing a covering portion interposing portion 41 having a different Young's modulus from the joint portion 40 between the piezoelectric vibration element 20 and the vibrating body 10, the resonance frequencies are not partially aligned, and the sound pressure peak at the resonance point is reduced. It becomes gentle. For this reason, even if the sound pressure is increased, stress is less likely to concentrate at the boundary of the joint 40 (the interface between the piezoelectric vibration element 20 and the joint 40 and the interface between the vibrating body 10 and the joint 40) at a specific frequency. The piezoelectric vibrating element 20 is prevented from peeling off the vibrating body 10 and the frequency characteristics are prevented from fluctuating. Furthermore, it can be set as the acoustic generator which has the outstanding frequency characteristic which suppressed peak dip by shifting resonance. The covering portion intervening portion 41 and the joint portion 40 will be described in detail later.

  The frame body 30 plays a role of holding the vibrating body 10 and forming a fixed end of vibration. For example, as shown in FIG. 1B, a frame body 30 is configured by joining a rectangular upper frame member 30a and a lower frame member 30b in the vertical direction. And the outer peripheral part of the vibrating body 10 is pinched | interposed between the upper frame member 30a and the lower frame member 30b, and it fixes in the state which provided predetermined tension. Therefore, the acoustic generator 1 including the vibrating body 10 with less deformation such as deflection even when used for a long time is obtained.

  The thickness and material of the upper frame member 30a and the lower frame member 30b are not particularly limited, but in the present embodiment, for example, stainless steel having a thickness of 100 to 5000 μm, for example, because it is excellent in mechanical strength and corrosion resistance. The material made from is used.

  The material of the upper frame member 30a and the lower frame member 30b is not limited to stainless steel, and may be any material that is more difficult to deform than the covering portion 50. For example, hard resin, plastic, engineering plastic, ceramics, glass, etc. In the present embodiment, the material and thickness of the upper frame member 30a and the lower frame member 30b are not particularly limited. Further, the frame shape is not limited to the rectangular shape, and a part or all of the inner peripheral portion or the outer peripheral portion may be circular or elliptical, or the inner peripheral portion or the outer peripheral portion may be rhombus.

  Moreover, in the acoustic generator 1, as shown in FIG. 1B, the piezoelectric vibration element 20 and the vibration surface 10a of the vibrating body 10 are covered with a covering portion (covering layer) 50 made of resin. For example, the covering portion 50 is configured to cover the piezoelectric vibration element 20 and the like by pouring resin into the frame of the upper frame member 30 a of the frame body 30. In FIG. 1A, the covering portion 50 is not shown for easy understanding.

  The resin forming the covering portion 50 is, for example, an epoxy resin, an acrylic resin, a silicon resin, or rubber, but these are examples and are not limited. Thus, by covering the piezoelectric vibration element 20 with the covering portion 50, an appropriate damping effect can be induced, and the resonance phenomenon can be suppressed and the difference between the resonance peak and the dip can be further reduced. preferable. Furthermore, the piezoelectric vibration element 20 can be protected from the external environment.

  In the acoustic generator 1 according to the present embodiment, all of the vibration surface 10a of the vibrating body 10 is covered with the covering portion 50, but it is not necessary to cover all of them. That is, in the acoustic generator 1, the piezoelectric vibration element 20 and at least a part of the vibration surface 10 a of the vibrating body 10 provided with the piezoelectric vibration element 20 may be covered with the covering portion 50.

  Here, the joint part 40 and the covering part interposing part 41 described above will be described in detail. 2 is a schematic plan view showing an example of the shape of the joint portion 40 and the covering portion intervening portion 41, and FIG. 3 is an enlarged sectional view taken along the line BB ′ of FIG. It is.

  In FIG. 2, for easy understanding, the outer shape of the piezoelectric vibration element 20 is indicated by a broken line, the joining portion 40 and the covering portion intervening portion 41 are seen through, and the covering portion interposing portion 41 is hatched. It is attached. In FIG. 3, the piezoelectric vibration element 20 is shown in a simplified manner, and the joint portion 40 is also shown expanded and deformed in the vertical direction.

  While the joint 40 is formed so as to be positioned near the center in a plan view between the vibrating body 10 and the piezoelectric vibrating element 20, as shown in FIGS. 2 and 3, the piezoelectric member 10 on the vibrating surface 10a of the vibrating body 10 is piezoelectric. The outer periphery 20a of the vibration element 20 is configured to have a portion (gap) where the joint portion 40 is not formed.

  The covering portion intervening portion 41 is a portion (gap) where the joint portion 40 is not formed when the piezoelectric vibration element 20 is covered with the covering portion 50, that is, the outer periphery of the piezoelectric vibration element 20 in the vibration surface 10 a of the vibrating body 10. It is formed by filling and filling the resin that will become the covering portion 50 into the portion along 20a.

  As described above, the sound generator 1 according to the present embodiment has the covering portion intervening portion 41 between the vibrating body 10 and the piezoelectric vibrating element 20, in other words, the vibrating body 10 and the piezoelectric vibrating element 20. Since a part of the covering portion 50 enters a gap existing between the covering portion 50 and the vibrating body 10, the covering portion interposed portion 41 and the piezoelectric vibration element 20 are joined. As a result, the bonding strength between the vibrating body 10 and the piezoelectric vibrating element 20 can be improved, and the peeling of the piezoelectric vibrating element 20 from the vibrating body 10 can be suppressed, and the frequency characteristics can be prevented from fluctuating. .

  Further, even if stress is generated by vibration or external impact, the stress in the vicinity of the piezoelectric vibration element 20 is concentrated on the covering portion intervening portion 41 made of a resin having a relatively low Young's modulus, and a joint having a relatively high Young's modulus. By being absorbed at the interface between the joint 40 and the covering portion intervening portion 41, the joining between the joining portion 40, the piezoelectric vibration element 20 and the vibrating body 10, and the joining between the vibrating body 10 and the covering portion 50 are maintained, and the frequency characteristics are maintained. Can be prevented from fluctuating.

  In particular, by providing a covering portion interposing portion 41 having a different Young's modulus from the joint portion 40 between the piezoelectric vibration element 20 and the vibrating body 10, the resonance frequencies are not partially aligned, and the sound pressure peak at the resonance point is reduced. It becomes gentle. Therefore, even if the sound pressure is increased, it becomes difficult for stress to concentrate at the boundary of the joint portion 40 at a specific frequency, and the piezoelectric vibration element 20 is prevented from being peeled off from the vibrating body, thereby preventing the frequency characteristics from fluctuating. . Furthermore, it can be set as the acoustic generator which has the outstanding frequency characteristic which suppressed peak dip by shifting resonance.

  In addition, since the covering portion intervening portion 41 along the outer periphery 20a of the piezoelectric vibration element 20 having a large strain is made of a resin having a large mechanical loss, the vibration loss is increased, and the vibrating body 10 is spread over a wide frequency range. The peak shape of the sound pressure at the resonance frequency of the sound pressure can be made smooth, and the difference between the resonance peak and the dip (valley between the resonance peaks) in the frequency characteristics of the sound pressure is reduced to minimize the frequency variation of the sound pressure. The sound quality can be improved.

  Here, as shown in FIG. 2, the covering portion intervening portion 41 as a part of the covering portion 50 has a central axis C of the piezoelectric vibration element 20 orthogonal to the vibration surface 10 a of the vibrating body 10 (the piezoelectric vibration element 20 is planar). It is preferable that the shape be asymmetric with respect to the axis passing through the center of gravity when viewed and perpendicular to the vibration surface 10a of the vibrating body 10). That is, it is preferable that the covering portion intervening portion 41 has a shape having no symmetry such as rotational symmetry with respect to the central axis C of the piezoelectric vibration element 20.

  Thereby, the magnitude | size of the coating | coated part interposition part 41 can be varied with places. Therefore, the width of the resonance peak can be made wider and the height can be lowered. Further, the difference between the resonance peak and the dip (the valley between the resonance peaks) can be reduced to further suppress the frequency fluctuation of the sound pressure, thereby improving the sound quality. Can be improved.

  As shown in FIG. 2, the covering portion intervening portion 41 as a part of the covering portion 50 according to the present embodiment is disposed over the entire outer periphery 20 a of the piezoelectric vibration element 20.

  As described above, when the entire outer periphery 40 a of the joint 40 is located inside the outer periphery 20 a of the piezoelectric vibration element 20, in other words, along the outer periphery 20 a of the piezoelectric vibration element 20 on the vibration surface 10 a of the vibrating body 10. In the case where there is a gap over the entire circumference, the covering portion intervening portion 41 as a part of the covering portion 50 is disposed over the entire circumference along the outer periphery 20a of the piezoelectric vibration element 20, so that the vibrating body 10 and the piezoelectric vibration are provided. The bonding strength with the element 20 can be further improved, and the sound quality can be further improved by further reducing the difference between the resonance peak and the dip (the valley between the resonance peaks) in the frequency characteristics of the sound pressure.

  However, the acoustic generator of the present embodiment is not limited to this, and for example, the covering portion intervening portion 41 may be disposed at least at a part of the outer periphery 20a of the piezoelectric vibration element 20.

  For example, if the covering portion intervening portion 41 is disposed at a corner of the piezoelectric vibration element 20 in a plan view, where stress due to vibration of the piezoelectric vibration element 20 itself is likely to concentrate, the above-described bonding area increases, and thus the vibration body 10 and the piezoelectric element are piezoelectric. The bonding strength with the corner portion of the vibration element 20 can be improved, and the peeling of the piezoelectric vibration element 20 from the vibration body 10 can be suppressed.

  Further, as shown in FIG. 4, a part of the outer periphery 40 a of the joint portion 40 is located inside the outer periphery 20 a of the piezoelectric vibration element 20, and the other part is located outside the outer periphery 20 a of the piezoelectric vibration element 20. In other words, in other words, there is a gap partially along the outer periphery 20a of the piezoelectric vibration element 20 on the vibration surface 10a of the vibrating body 10, and the joint 40 protrudes at other portions where no gap is formed. In the case where the vibration body 10 alone vibrates around the piezoelectric vibration element 20 and the vibration area in the structure in which the vibration body 10 and the joint 40 are joined together, the respective resonance conditions are different. Resonance frequencies are less likely to be aligned, and peak dip can be further suppressed.

  Further, by providing the covering portion intervening portion 41 as a part of the covering portion 50 in the partially formed gap, the covering portion interposing portion 41 and the joint portion 40 are joined in an intricate manner, and the vibrating body 10 and the piezoelectric member are joined. The joint strength with the vibration element 20 is improved, and the sound quality can be improved by reducing the difference between the resonance peak and the dip (the valley between the resonance peaks) in the frequency characteristic of the sound pressure.

  In addition, as shown in FIG. 2, the shape (outer peripheral surface) of the outer periphery 40a that contacts the covering portion intervening portion 41 of the joint portion 40 has irregularities in plan view. Specifically, the concave portions and the convex portions are alternately continuous. Preferably it is shaped.

  As a result, the resonance condition of the vibration transmitted from the piezoelectric vibration element 20 to the vibrating body 10 continuously changes, and the peak shape of the sound pressure at the resonance frequency of the vibrating body 10 is further smoothed over a wide frequency range. be able to.

  Further, as shown in FIG. 3, the interface between the joint portion 40 and the covering portion intervening portion 41, in other words, the outer peripheral surface in contact with the covering portion interposing portion 41 of the joint portion 40 is orthogonal to the vibration surface 10 a of the vibrating body 10. It is preferable to have a groove portion 40b having a curved shape in a cross section (for example, a cross section taken along line BB ′). In detail, it is preferable that the groove part 40b is made into the convex curve shape toward the junction part 40, for example from the coating | coated part interposition part 41. FIG.

  Thereby, in the coating process in which the resin for forming the covering portion 50 is applied to the piezoelectric vibration element 20, the portion where the joint portion 40 is not formed can be easily filled with the resin, and the covering portion intervening portion 41 can be easily formed. Become.

  Note that, as described above, the covering portion intervening portion 41 is disposed between the vibrating body 10 and the piezoelectric vibration element 20 at a portion where the joining portion 40 is not formed, and thus the shape and thickness of the joining portion 40 are changed. Only by this, the shape and thickness of the covering portion intervening portion 41 can be easily changed.

  Further, as shown in FIG. 5, the sound generator 1 may be configured to have a void 42 in a covering portion intervening portion 41 as a part of the covering portion 50. The void diameter at this time is, for example, 0.01 to 100 μm, and the void ratio is, for example, 0.01 to 10%. As described above, the inside of the covering portion intervening portion 41, between the covering portion 50 and the vibrating body 10, between the covering portion 50 and the piezoelectric vibration element 20, and between the covering portion 50 and the joint portion 40. By the presence of the void 42 in at least one of them, the stress generated by the vibration of the member including the vibrating body 10 and the covering portion 50 integrated with the piezoelectric vibration element 20 is concentrated in the vicinity of the void 42 and the local area in the vicinity of the void 42 is obtained. Strain increases. As a result, energy generated by vibration can be effectively lost, so that the difference between the resonance peak and the dip can be further reduced.

  Furthermore, as shown in FIG. 6, there is a gap 43 between the covering portion intervening portion 41 as a part of the covering portion 50 and at least one of the vibrating body 10, the piezoelectric vibration element 20, and the joint portion 40. Also good. The diameter of the gap 43 at this time is, for example, 0.05 to 100 μm. A region where vibration is propagated from the piezoelectric vibration element 20 to the vibrating body 10 via the joint portion 40, a region where vibration is propagated via air, and a region where vibration is propagated to the vibrating body 10 via the covering portion intervening portion 41 And mixed. At this time, since the propagation speed inside the bonding material 21 and the propagation speed in the air are different, the resonance frequency is further non-uniform, and the acoustic generator 1 having very excellent frequency characteristics can be obtained.

  As described above, in the sound generator 1, at least a part of the outer periphery 40 a of the joint portion 40 is located on the inner side of the outer periphery 20 a of the piezoelectric vibration element 20, and between the vibrating body 10 and the piezoelectric vibration element 20. Since a part of the covering portion 50 is interposed, the bonding strength between the vibrating body 10 and the piezoelectric vibrating element 20 can be improved, and the peeling of the piezoelectric vibrating element 20 from the vibrating body 10 can be suppressed. Can be prevented from fluctuating.

  Here, with reference to FIG. 7, the sound generator 1 which concerns on the modification in this embodiment is demonstrated. FIG. 7 is an enlarged cross-sectional view taken along the line B-B ′ of FIG. In the following, the same components as those in the previous embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 7, in the acoustic generator 1 according to the modification, the outer peripheral surface of the joint portion 40 has a wedge-shaped groove in a cross section (for example, a cross section taken along line BB ′) orthogonal to the vibration surface 10 a of the vibrating body 10. 40c. Specifically, the groove portion 40c has, for example, a shape having two substantially straight sides forming a predetermined angle near the center in the thickness direction between the vibrating body 10 and the piezoelectric vibration element 20 in a cross-sectional view taken along the line BB ′. Is done.

  As described above, in the acoustic generator 1 according to the modification, the interface between the joint portion 40 and the covering portion intervening portion 41 includes the wedge-shaped groove portion 40c in a cross-sectional view. The sound pressure peak can be further smoothed. Furthermore, the above-described void is easily formed at the wedge-shaped tip portion in the groove 40c, so that the energy generated by the vibration can be more effectively lost, and the difference between the resonance peak and the dip can be further reduced.

  As shown in FIG. 8, the sound generator 2 can be configured by housing the sound generator 1 having the above-described configuration in a resonance box 200. The resonance box 200 is a housing that houses the sound generator 1, and resonates the sound emitted from the sound generator 1 and radiates it as sound waves from the housing surface. Such a sound generator 2 can be used alone as a speaker, and can be suitably incorporated into various electronic devices 3, for example.

  As described above, since the difference between the resonance peak and the dip in the frequency characteristic of sound pressure, which is disadvantageous in the piezoelectric speaker, can be reduced, the sound generator 1 according to the present embodiment can be used for a mobile phone or a thin television. Alternatively, it can be suitably incorporated into the electronic device 3 such as a tablet terminal.

  The electronic device 3 to which the sound generator 1 can be incorporated is not limited to the above-described mobile phone, flat-screen TV, tablet terminal, and the like, and for example, a refrigerator, a microwave oven, a vacuum cleaner, a washing machine, and the like. Conventionally, home appliances that have not been focused on sound quality are also included.

  Here, the electronic device 3 including the above-described sound generator 1 will be briefly described with reference to FIG. FIG. 9 is a block diagram of the electronic device 3. The electronic device 3 includes the acoustic generator 1 described above, an electronic circuit connected to the acoustic generator 1, and a housing 300 that houses the acoustic generator 1 and the electronic circuit.

  Specifically, as illustrated in FIG. 9, the electronic device 3 accommodates an electronic circuit including a control circuit 301, a signal processing circuit 302, a wireless circuit 303 as an input device, an antenna 304, and these. And a housing 300. Although the wireless input device is shown in FIG. 9, it can be provided as a signal input by normal electric wiring.

  In addition, description was abbreviate | omitted here about the other electronic members (for example, devices and circuits, such as a display, a microphone, and a speaker) with which the electronic device 3 is provided. In FIG. 9, one acoustic generator 1 is illustrated, but two or more acoustic generators 1 and other transmitters may be provided.

  The control circuit 301 controls the entire electronic device 3 including the wireless circuit 303 via the signal processing circuit 302. An output signal to the sound generator 1 is input from the signal processing circuit 302. Then, the control circuit 301 generates a sound signal S by controlling the signal processing circuit 302 from the signal input to the radio circuit 303 and outputs the sound signal S to the sound generator 1.

  In this way, the electronic device 3 shown in FIG. 9 incorporates the small and thin sound generator 1 and reduces the difference between the resonance peak and the dip as much as possible to suppress the frequency fluctuation as much as possible. It is possible to improve the sound quality as a whole even in a high sound region including a low sound region having a low sound level.

  In FIG. 9, the electronic apparatus 3 directly mounting the sound generator 1 is exemplified as the sound output device. However, as the sound output device, for example, the sound generator 2 in which the sound generator 1 is housed in the housing is mounted. It may be the configuration.

  Further, in the above-described embodiment, an example in which one piezoelectric vibration element 20 is disposed on the vibrating body 10 is illustrated, but two or more piezoelectric vibration elements 20 may be disposed. When there are two or more piezoelectric vibration elements 20, the piezoelectric vibration elements 20 may be disposed on the same surface of the vibration surface 10 a of the vibrating body 10 or on both surfaces. Further, although the piezoelectric vibration element 20 is rectangular in plan view, it may be square. Further, although the example in which the piezoelectric vibration element 20 is disposed at the approximate center of the vibration surface of the vibration body 10 is illustrated, the piezoelectric vibration element 20 may be disposed at a position deviated from the vibration surface center of the vibration body 10.

  Further, as the piezoelectric vibration element 20, a so-called bimorph type laminated type is illustrated, but a unimorph type piezoelectric vibration element can also be used.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 Sound generator 2 Sound generator 3 Electronic device 10 Vibrating body 20 Piezoelectric vibration element 30 Frame body 40 Joint part 40b, 40c Groove part 41 Covering part interposition part 42 Void 43 Cavity 50 Covering part 200 Resonance box (housing)
300 Housing 301 Control circuit 302 Signal processing circuit 303 Radio circuit 304 Antenna

Claims (9)

A vibrating body,
An exciter that vibrates upon receipt of an electrical signal;
A joint for joining the exciter on the vibrator;
A covering portion provided from the exciter to the vibrating body,
At least part of the outer periphery of the joint portion is located inward from the outer circumference of the exciter, a portion of the cover portion is interposed between the exciter and the vibrator, one of the covering portion The acoustic generator is characterized in that the portion has an asymmetric shape with respect to the central axis of the exciter perpendicular to the vibration surface of the vibrating body . A vibrating body,
An exciter that vibrates upon receipt of an electrical signal;
A joint for joining the exciter on the vibrator;
A covering portion provided from the exciter to the vibrating body;
With
At least a part of the outer periphery of the joint is located on the inner side of the outer periphery of the exciter, and a part of the covering part is interposed between the vibrator and the exciter, and the joint the portion of the cover portion and is in contact, the outer peripheral surface characteristics and to Ruoto sound generator that you have to have a concavo-convex in contact with a portion of the cover portion of the joint. The outer peripheral surface of the joint is sound generator according to claim 1 or claim 2 characterized by having a groove of wedge-shaped in a cross section perpendicular to the plane of vibration of the vibrating member. The entire outer periphery of the joint portion is located inside the outer periphery of the exciter, and a part of the covering portion is disposed over the entire periphery along the outer periphery of the exciter. The sound generator according to any one of claims 1 to 3 . A vibrating body,
An exciter that vibrates upon receipt of an electrical signal;
A joint for joining the exciter on the vibrator;
A covering portion provided from the exciter to the vibrating body;
With
A part of the outer periphery of the joint is located inside the outer periphery of the exciter, and the other part is located outside the outer periphery of the exciter, between the vibrator and the exciter. features and to Ruoto sound generator that part of the cover portion is interposed. A vibrating body,
An exciter that vibrates upon receipt of an electrical signal;
A joint for joining the exciter on the vibrator;
A covering portion provided from the exciter to the vibrating body;
With
At least a part of the outer periphery of the joint is located inside the outer periphery of the exciter, and a part of the covering part is interposed between the vibrator and the exciter,
Features and to Ruoto sound generator that you have to have a void in a portion of the cover portion. A vibrating body,
An exciter that vibrates upon receipt of an electrical signal;
A joint for joining the exciter on the vibrator;
A covering portion provided from the exciter to the vibrating body;
With
At least a part of the outer periphery of the joint is located inside the outer periphery of the exciter, and a part of the covering part is interposed between the vibrator and the exciter,
The covering portion and the vibrating body, features and be Ruoto sound generator that you have voids exist between at least one of said exciter and said junction. The sound generator according to any one of claims 1 to 7 ,
A sound generation device comprising: a housing for housing the sound generator. The sound generator according to any one of claims 1 to 7 ,
An electronic circuit connected to the acoustic generator;
A housing for housing the electronic circuit and the acoustic generator,
An electronic apparatus having a function of generating sound from the sound generator.

Images